public class stringstudent {
        public static void main(String[] args) {
                String id = "20233011012";
                int length = id.length();
                System.out.println("学号的长度是"+length);
                char ch = id.charAt(3);
                System.out.println("学号的第四位是"+ch);
                char array[] = new char[2];

                id.getChars(9,11,array,0);
                System.out.println("学号的后两位是"+String.valueOf(array));
        }


}
